Prevalence of Extended-Spectrum β-Lactamases CTX-M-8 and CTX-M-2-Producing Salmonella Serotypes from Clinical and Nonhuman Isolates in Brazil

Abstract

We characterized extended-spectrum β-lactamases (ESBL) enzymes among Salmonella strains isolated in Brazil from 2009 to 2014. Salmonella recovered from both clinical and nonhuman (food, poultry, and environment) sources were subjected to antimicrobial susceptibility testing. β-lactamases genes were detected by polymerase chain reaction/sequencing; plasmid profiles and transferability were assessed by S1-pulsed field gel electrophoresis (PFGE). Genetic diversity was evaluated by XbaI-PFGE. Out of 630 Salmonella strains screened, 46 displayed ESBL phenotype, distributed across 11 different serotypes. bla and bla genes were detected at frequencies of 47% and 41%, respectively. bla and bla were also detected but in lower frequencies (4%, 2%). bla gene was detected in 22% of the strains. Most of the ESBL genes were transferable by conjugation, and the respective bla gene was detected in the recipient strain, indicating the location of ESBL determinants on transferable plasmids. XbaI-PFGE revealed genomic diversity of Salmonella Typhimurium bearing bla, bla, bla, and bla genes. Salmonella Muenchen (harboring bla) and Salmonella Corvallis (bla and bla) showed clonal relatedness within respective serotypes. Our findings underscore the occurrence of diverse ESBL genes in several Salmonella serotypes, reinforcing the need for continuous surveillance of resistance genes circulating in human and nonhuman sources.

Antimicrobial resistance and genetic diversity in ceftazidime non-susceptible bacterial pathogens from ready-to-eat street foods in three Taiwanese cities

“…Researchers studying different types of salads in Portugal and Switzerland have reported that RTE food pathogens share the same ESBL genes as clinical isolates collected from hospital patients, suggesting the potential for commensal bacteria to act as antibiotic-resistant gene reservoirs, especially in hospital settings 9 , 20 . Further, ESBL-producing Enterobacteriaceae isolates have been reported in beef burger, seafood, and raw vegetable samples 15 , 31 , 32 . Based on these reports, ESBL gene sources in human food chains include both RTE and non-RTE food products.…”

Antimicrobial Resistance in Farm Animals in Brazil: An Update Overview

“…Table 5 describes the source, geographic location of sampling, and bla genes found in studies that reported ESBL and pAmpC-encoding genes in food or food-producing animals in Brazil. In Salmonella, bla CTX-M-2 was identified in non-transferable and conjugative plasmids of 90 to 290 kb. These plasmids belonged to IncI1, IncHI2, or non-typable incompatibility groups [36,145,155,156]. Part of isolates characterized by Fernandes and coworkers was not able to transfer bla CTX-M-2 to E. coli, suggesting a possible chromosomal location of this gene [145].…”

“…Studies indicate that these genes are mainly carried by E. coli and nontyphoid Salmonella, but also by Escherichia fergusonii, Klebsiella pneumoniae, Citrobacter diversus, and Proteus mirabilis [136][137][138][139][140]. Reports include animals on farms [36,[136][137][138][141][142][143][144][145][146][147], whole carcasses, or meat pieces available in Brazilian retail markets [69,136,138,140,145,148,149], and exported chicken meat [150][151][152]. The same genes were detected in turkeys with clinical signs of colibacillosis [153].…”

“…For instance, Salmonella sp. and E. coli producing bla CTX-M-variants have been detected in poultry farms environment and on the surface of flies from dairy farms, respectively [124,145]. In addition, a study has shown that the prophylactic administration of ceftiofur to one-day-old broiler chicks may be associated with early carriage of ESBL-producing E. coli in the gut of these animals [154].…”

“…These plasmids belonged to IncI1, IncHI2, or non-typable incompatibility groups [36,145,155,156]. Part of isolates characterized by Fernandes and coworkers was not able to transfer bla CTX-M-2 to E. coli, suggesting a possible chromosomal location of this gene [145]. In contrast, in E. coli, most studies suggest a chromosomal location of bla CTX-M-2 with a few reports of this gene in plasmids belonging to IncK, IncHI2, IncP incompatibility groups ranging from 35 to 280 kb [137,139,146,147,157].…”